If already not done so, you can search the following criteria/link per Gabe Botar's contributions to the success of grafting such.
(Chokecherries are not compatible with the true cherries in f. above)

Yes...pin cherry is fine but not choke.

I recall reading of chokecherry not being compatible, though appreciate the confirmation ... though, too bad, cause I have a large patch of them along the side of my garden and maybe I'll just graft some superior chokecherry selections onto them.

Yes...that's what I did..some native which I've never seen black knot on it and a Lee red and yellow.

Indeed, there are some very good chokecherries to be found along the roads and fields and some being worthy of propagation.

If the Saskatchewan cherries work on amur cherry then take another look at "Pl.Sc.335" point f. and g. and give some a shot. It gives credit to the chokecherry above the amur but if they like each other it may be a good thing if and as long as grafting amur is the middle one.

My own experience in Alaska I have prunus padus and pin cherry growing almost always on amur. The Saskatchewan cherry I have never tried on amur.

No wait. I do remember once grafting amur above one of the chokecherries. It survived better that way then some pin cherry grafts I did in the same tree but still failing a year after, however they were performing as amur bud grafts. According to Thean bud grafts are not reliable in the prunus world that far north. All my fruiting sweet and sour cherry buds die that far up.

Got some Saskatchewan cherries on Amur for testing...sometimes they abort but have some 3 or 4 years now, Juliet, Chrimson Passion and Cupid...still a little early to say if it's good. Perhaps one should try a Amur interstem on chokecherry...might just do it this year.

Yes, I just might try the Amur interstem, first I'll have to go looking in town to find some Amur trees.

Thanks for your observations regarding the Amur rootstock. I think I'll instead just stick to grafting chokecherry to chokecherry and the Sask cherries to pincherries growing along my driveway, what the heck if birds or humans come along and eat some. Unfortunately, I will be away and unable to attend the scion exchange.

I tried grafting Juliette and Crimson Passion to chokecherry last year. Some of the Juliettes leafed out, but none survived the summer.